Thermographic recording using vaporizable material and colored particle development

ABSTRACT

Process of reproducing the image pattern of an original having a vaporizable material at least in the image areas by heating the image areas to cause the material to vaporize and condensing the vaporized material on the surface of a receiving sheet placed in contact with the original. The material is vaporized in the image areas by exposure to infrared radiation. The condensed latent image of material on the receiving sheet is visualized by the application of colored particles which adhere to the material. The visualized image may subsequently be transferred to another sheet.

[ Feb. 12, 1974 United States Patent 1191 Gundlach THERMOGRAPHIC RECORDING USING /1960 Tien....... 250/65 3/1963 Gulko 250/65 2/1964 Meissner....... 250/65 10/1966 Clark et 250/65 X FOREIGN PATENTS OR APPLICATIONS 2/1961 South Africa........1........... 101/149.4

[22] Filed:

Primary ExaminerWil1iam F. Lindquist Attorney, Agent, or FirmBrumbaugh, Graves, Donohue & Raymond [57] ABSTRACT Process of reproducing the image pattern of an original having a vaporizable material at least in the image areas by heating the image areas to cause the material to vaporize and condensing the vaporized material on the surface of a receiving sheet placed in contact with the'original. The material is vaporized in the image Related US. Application Data [63] Continuation of Ser. No. 110,711, May 17, 1961,

abandoned.

[52] US. 250/318, 101/470, 117/17.5 [51] Int. Cl. G011! /10 [58] Field of Search 101/1494, 149.5, 470; 117/17, 117/17.5, 37; 250/65 T [56] References Cited UNITED STATES PATENTS areas by exposure to infrared radiation. The condensed latent image of material on the receiving sheet is visualized by the application of colored particles 250/65 which adhere to thematerial. The visualized image 1 7 may subsequently be transferred toanother sheet.

171 .5 Miller et a1. 18 Claims, 4 Drawing Figures Andrus Murray......;........ Schaffert et a1. Hoover...............

HIGH INTENS IIilIIIlI-I TY LIGHT SOURCE PAYNE-Brawn I HIGH INTENSITY LIGHT SOURCE l l l F/GIZ THERMOGRAPIIIC RECORDING USING VAPORIZABLE MATERIAL AND COLORED PARTICLE DEVELOPMENT ber changes color in areas which are sufficiently heated or raised in temperature thereby forming a reproduction of the original being copied.

The thermographic process has certain disadvantages. To date, the copy sheet has been somewhat off color in the sense of the usual white sheet and thus is not entirely acceptable for all uses. The copy paper also has a peculiar feel and the market has not accepted this material as equivalent to other types of copy. Further the copy produced is dependent on conduction of heat from one surface to another which at best is inefficient and non-uniform and results in un-sharp non-uniform and sometimes weak copy. Further the copy produced has limited utility as a copy only and in addition will not serve for permanent records due to its sensitivity to aging effects. A still further disadvantage of known thermographic processes is that they irradiate through the body of either the original or a heat sensitized paper neither of which are normally good transmitters of light. Due to the illumination intensity required to produce sufficient heat transfer between the image surface and the sensitive surface, the lighttransmitting member must be very thin to compensate for its poor transmission qualities. Thus machines using these processes are severely limited either in the originals they can accept or heat sensitive papers they utilize.

Now, in accordance with the instant invention, selective heating of an original to be reproduced causes the formation of a condensate on a copy receiving medium conforming in configuration to the original. This condensate may be visualized if desired or may be used in the condensate form. Forming images in this manner has the advantage of creating an image of macroscopic material. Further it may be given any of a great number of physical properties and its formation is not dependent on conductivity of heat between separated surfaces. Also it is possible in accordance with the present invention to form an image on any solid surface such as cartons, boxes, walls, books, etc., without the need of special treatment of such surface. It is therefore an object of the instant invention to devise novel processes ofimage formation to reproduce copy from an original.

It is a further object of this invention to devise a novel method of forming a deposition on a copy receiving member conforming in configuration to an original to be reproduced through selectively heating the original.

It is a further object of this'invention to disclose novel techniques of forming a visible image conforming in configuration to an original to be reproduced employing selective heating of the original and development of the copy receiving medium.

Additional objects of the present invention will be more readily apparent from the following disclosure and description, especially when read in conjunction with the accompanying drawings, in which:

FIG. 1 is a diagrammatic illustration of anembodiment of forming a condensate of an original on a copy receiving medium in accordance with the invention;

FIG. 2 is a diagrammatic illustration of condensate development;

FIG. 3 is a diagrammatic illustration of an embodiment of transfer of a developed image; and,

FIG. 4 is a diagrammatic illustration of an embodiment of image fixing.

For a better understanding of this invention, refer ence is now had to FIG. 1 wherein is shown an embodiment of the invention to obtain a condensate pattern on a reproducing member which corresponds to the image on an original to be reproduced. Original bears an image represented by the solid segments in the diagram. Unlike the commercially available thermographic processes, which are somewhat limited as to what can be reproduced, substantially any original 7 bearing a visible image and volatile material can be reproduced in accordance with the present invention. By way of example, original 10 may be newspaper. In the illustrated embodiment transparent sheet or member 11 is placed in contact with the image surface of the original. Reproducing member 11 in this embodiment is suitably transparent or translucent glass, transparent or translucent plastic such as acetate or other similar transparent or translucent material. Reproducing member 11 is characterized as having a surface generally non-absorbent to volatile materials or vapors and this surface is positioned in facing contact with original 10 to be reproduced. Following the formation of the assembly of original 10 against reproducing member 11, high intensity illumination source 112 is directed toward member 11 so that rays of illumination 13 pass through member 11 and impinge on the image surface or original l0. Illumination source 12 is a high energy source such as a high power electronic photo-flash lamp or an infrared lamp or may be heat lamp units such as are used in a thermographic copying machine. A typical thermographic copying machine is sold by Minnesota Mining and Manufacturing Company, St. Paul; Minnesota, under the trademark Thermoifax. The light energy required should be in the range between about to watt seconds per square inch depending on the volatility of the materials as will appear below. It is preferable that the light source provide energy primarily in the spectra that will be absorbed by the image colors in the original. Due to the impingement of the high intensity light on the image pattern of the original, volatile materials, in or on the surface of the image segments 15, volatilize and condense in corresponding areas on the adjacent surface of reproducing member 11.

While not to be considered as limiting, the mechanism of operation is believed dependent upon the generation of sufficient heat by the absorption of the light in colored or black areas of the original copy causing vaporization and the deposit of a condensate. In some printing material such as newspaper there is an appreciable amount of volatile-oils and tars present in the print. Heat as from an intense light source will cause these oils and tars to volatilize or evaporate and recondense upon touching a relatively cool surface. In other printing material, such as lithographic copy, similar condensates may be obtained due to films of volatile material which are present on the printing surface.

Such a volatile material may be water, alcohol, or any one of various oils or oily materials. A highly volatile material requires less illumination energy, but has shorter persistence as a condensate image. With a volatile material such as a petroleum machine lubricating oil of the type used for sewing machine oil, a suitable illumination energy is about 70 watt seconds per square inch.

Although a transparent receiving member is shown and discussed in connection with FIG. 1, it should be apparent that what is necessary is a transparent or substantially transparent light path to the original copy. Accordingly, if the original is on such a base, the receiving member need not have these qualities but may be opaque and illumination may be provided from the free side of the original.

Once the condensate image is obtained it may be developed or visualized by any one of a number of techniques such as illustrated in the embodiment of FIG. 2. In FIG. 2 the condensate is illustrated as small round circles or droplets 16 which in this embodiment have an oil base. The image is developed by use of magnetic brush 17 which in the embodiment illustrated comprises a magnet 20 enclosed in a non-magnetic envelope 18. Magnetic brushes suitable for use in accordance with the present invention are described in application Ser No. 739,453 filed May 23, I958, and now U.S. Pat. No. 3,015,305 in the name of Richard H. Hall and John W. Bird, Jr. The composite of magnet 20 and envelope 18 is used to present fine particles of magnetic material 21 to the condensed image on reproducing member 11. The magnetic material 21 may be any one of a wide range of ferrous or ferrite magnetic powders such as carbonyl iron powder. Preferably the particle size of these powders is between about 4 microns and 17 microns in diameter. Particle size is chosen to give the best image. When the particles are too small, excessive background material is developed and when they are too large, there is a loss of image density. Other methods of development include the various known xerographic development techniques known to the art. For example, cascading any of the various known xerographic developing powders across the condensate image on the surface of the reproducing member will result in a visible or developed image. Suitable powders for this material have been found to be carbonyl iron, charcoal and xerographic resin toners such as disclosed in U.S. Pat. No. 2,753,308 to R. B. Landrigan. Other suitable materials have been used for developing the condensate image into a duplicating master. For example, such images have been developed with crystal violet dye powder to produce a spirit duplicating master. When the condensate is an oil having a vapor pressure less than water, a direct printing lithographic master may be made using the undeveloped condensate. The oil condensate itself has the waterrepellent ink-absorbent characteristics required for lithographic work. By using a transparent sheet, such as a transparent acetate or polyethylene film, for reproducing member 11, a reproducing master such as is valuable in a diazo duplicating process can be pro- ,duced. After the image is developed with a dark powder it may be suitably fixed by spraying with a transparent lacquer or plastic spray, by heating, or other conventional means.

While the image may be developed directly on the reproducing member 11 which may then be the final reproduced copy, it is frequently advantageous to transfer the image to more conventional paper. FIG. 3 illustrates an embodiment of such a transfer step. De veloped image 19 on the surface of reproducing mem' ber 11, which for this application can suitably be glass, is covered by a sheet of paper 22 having a thermoplastic coating 23. Coated papers suitable for this use are described in detail in U.S. Pats. Nos. 2,855,324 and 2,886,464 and may comprise white printing paper coating with a one-eighth mil to 1 mil thick polyethylene plastic. Transfer may be made by pressure such as by traversing the back surface of sheet 22 with pressure roller 25. The developed image material is thereby embedded into the polyethylene coating. When sheet 22 is separated from. reproducing member 11 the image will separate with sheet 22. When an image in accordance with the invention is developed with carbonyl iron powder and transferred in the manner just described to a polyethylene sheet or a polyethylene coated sheet, a novel duplicating master is produced that is somewhat analogous to a lithographic master. Polyethylene has a highly repellent surface to which few materials adhere. Carbonyl iron powder is readily embeddable in a polyethylene layer and this powder is wettable by water. Thus when a carbonyl iron powder image is transferred to a polyethylene surface, a water base ink may be applied to the surface and will wet the surface only in the areas of the carbonyl iron powder image. In a lithographic type of duplicator this master can be used to run copies printed with a water base ink.

Due to the possibility of smudging, and if the transferred image on its new base is to be used as permanent copy, a fixing process is frequently desirable. FIG. 4 shows an embodiment of a fixing device for fixing a powder image to a polyethylene surface. Heat source 26 can be an infrared lamp, thermal-wire elements or other conventional source of heat radiation. The polyethylene surface of the sheet 22, when softened by the heat, encapsulates or embeds the powder image particles.

As is apparent, the original condensate image may be produced directly onto a transparent or translucent thermoplastic sheet. Developing as discussed in connection with the embodiment of FIG. 2 and applying heat to the image bearing member or sheet as in the fixing embodiment shown in FIG. 4 will produce a suitable fixed image without the transfer step described in connection with FIG. 3.

The process above disclosed is subject to many variations within its scope. Below are given a few specific examples.

EXAMPLE I A 3 mil sheet of Kodapak (trademark of Eastman Kodak Company, Rochester, N.Y., and believed to designate a transparent film of cellulose acetate) was placed against a print bearing surface of a freshly printed newspaper sheet. The two sheets were then run through a Thermofax machine in a manner so that the heat source of the Thermofax machine irradiated the sheets from the side of the acetate film. The Thermofax machine used was a 15 ampere volt Secretary Model with the speed control set at the approximate midpoint. After leaving the machine the acetate film was separated from the newspaper sheet and the condensate image on the acetate film was developed with a magnetic brush method. The developing powder used for this example was Carbonyl lron Powder, Type HP, manufactured by General Dyestuff Corporation, Antara Chemicals Division, New York City and believed to be a common carbonyl iron in particulate form such that the particles vary between 4 and 17 microns in diameter. The developed image was pressure transferred between two pressure rollers to polyethylene coated paper. The image was then fixed on the coated paper in an oven at a temperature of 325 F. for 5 seconds. A readily legible highly resolved image was obtained.

EXAMPLE ll EXAMPLE III A condensate image was again obtained in a manner identical to that above and developed by cascading a charcoal powder consisting of particles 1 to 3 microns in diameter across the surface of the glass which faced the newspaper.

EXAMPLE [V The processused for this example was identical to that of Example ll, except that the condensate image was cascaded with apowder of carbonyl iron in which the particles ranged about 3 microns in diameter.

, Legible copy, slightly inferior quality to that produced by Example I, was obtained in each of Examples II, III, and IV.

EXAMPLE v A condensate image was produced on a 3 mil acetate film in-identical manner to that used in Example I. The condensate image was then developed with a magnetic brush and carbonyl iron powder and fixed by a clear plastic spray. (Crystal Clear Spray Coating No. 1300A available from Krylon Inc., Norristown, Pennsylvania, was used.) The image thus produced on the transparent I acetate film was run as a master in a diazo duplicating machine and produced highly resolved good quality reproductions.

EXAMPLE V] A spirit duplicating master was made from a newspaper original. A 3 mil Kodapak sheet was placed against afresh newspaper original and an electronic flash exposure was made as in Example ll] holding the lens of the flash unit within one-half inch of the acetate sheet. The image was developed by cascading powdered crystal violet dye across the acetate sheet. The acetate sheet was then clamped onto the drum of a spirit duplicating machine and 25 copies were run. No fixing or fusing t step was used in this example.

While the present invention has been described as carried out in specific embodiments thereof, there is no desire to be limited thereby, but it is intended to cover the invention broadly within the spirit and scope of the appended claims.

What is claimed is:

1. The process of producing a visible condensate pattern comprising positioning a patterned original carrying volatile material adjacent to a. reproducing member, illuminating the pattern of said patterned original with illumination energy amounting to between 25 and 150 watt seconds per square inch so that said volatile material is evaporated in the pattern configuration and condensed on said reproducing member, and applying a particulate development material to said reproducing member, said development material being characterized in that it is adhesive to the condensate and nonadhesive to the reproducing member.

2. The process of forming a reproduction of an origi nal image comprising positioning a freshly-inked original image in face-to-face contact with a sheet of cellulose acetate film, intensely illuminating said original image through said film so that volatile material in the ink of the original image is evaporated and forms a condensate on said film, separating said film from said original image and developing said condensate with a ferromagnetic powder having a particle size between 4 and 17 microns.

3. The process of image reproduction comprising positioning an image original carrying volatile material adjacent to a reproducing member, illuminating said image original with illumination energy of between 25 and 150 watt seconds per square inch or reproduction area to evaporate and form a condensate of said volatile material on the reproducing member in the pattern of the original image, and applying a particulate pow der of crystal violet to said condensate.

4. The process of image reproduction comprising positioning an image reproducing member in face-toface contact with an image original, selectively heating said image original causing volatile materials in said image areas to evaporate from the original and form a condensate on the image reproducing member, developing the condensate with a particulate colorant into a visible image, transferring said visible image to a transfer member and fixing said visible image on the transfer member.

5. The process of image reproduction as in claim 4 in which the particulate colorant is carbonyl iron powder and the transfer member is a sheet of paper coated with a thermoplastic film.

6. The process of image reproduction according to claim 5 in which said thermoplastic film is a polyethylene film.

7. The process of image reproduction according to claim 4 in which the transfer member comprises a thermoplastic layer and the said visible image is fixed on the transfer member by heating the thermoplastic layer so that the image particles become embedded and encapsulated therein.

8. The process of making a transparent master comprising positioning a transparent plastic sheet in faceto-face contact with an original carrying volatile substance on its image surface, intensely illuminating said original through the transparent plastic sheet so that heat is generated in the image areas of the original producing a condensate of the volatile substance on the transparent plastic sheet, separating said transparent plastic sheet from the original, developing the condensate with a particulate colorant and fixing the particles of the colorant to the plastic sheet.

9. The process of image reproduction comprising positioning an image-reproducing member facing an image original, selectively heating said image original causing volatile material in image areas to evaporate and form a condensate on the image-reproducing member in image configuration and developing the condensate with a particulate colorant into a visible image.

10. The process of original image reproduction comprising placing an original carrying a vaporizable material in at least image areas with its image side in contact with a transfer sheet, heating at least the image areas of said original to the vaporization point of said vaporizable material, condensing at least a portion of said vaporized material on the surface of said transfer sheet facing said original and visualizing said condensed material on said transfer sheet by dusting said transfer sheet with a colored particulate material which adheres to said condensed vaporizable material.

11. The process of reproducing an original image carrying volatilizable material comprising placing an image receiving member in contact with said original image, directing sufficient radiant energy upon said original image to volatilize said material, condensing said material on said receiving member in the configuration of said original image and dusting the condensed material with a colored particulate powder.

12. The process of reproducing a graphic image drawn upon a surface with material containing infrared absorbent and infrared volatilizable constituents, comprising placing an image receiving member in contact with said graphic image, volatilizing said constituents by directing radiant infrared-rich energy upon said surface, thereupon condensing said constituents on said receiving member in the same configuration as said graphic image, and thereupon visualizing said constituents by applying thereto a highly visible powder, said powder being characterized by mechanical adherence to said constituents.

13. The process of copying originals which comprises placing an original having a vaporizable material in image areas of the original with its image side in contact with a copy sheet; heating image areas of said original to evaporate said vaporizable material; condensing vaporizable material on said copy sheet facing said original; and developing the condensed material on said copy sheet by cascading said copy sheet with colored powder which adheres to said condensed material to form a developed image on said copy sheet.

14. The process of original image reproduction comprising placing the image side of an original having image-bearing areas and non-image bearing areas thereon adjacent to a transfer sheet, at least the image-bearing areas containing a vaporizable material that is adapted to be visualized subsequent to transfer to the transfer sheet by being contacted with a visible material capable of adhering thereto, heating the original at the imagebearing areas to an extent sufficient to vaporize at least a portion of the vaporizable material, and forming on the adjacent surface of the transfer sheet images consisting essentially of condensate of the vaporized material and corresponding to the image-bearing areas of the original by condensing at least a portion of the vaporized material on said adjacent surface in a pattern corresponding to the image pattern of the original.

15. The process according to claim 14 further comprising visualizing the pattern of condensed material on the transfer sheet by contacting the condensed material with a visible material capable of adhering thereto.

16. The process according to claim 15 further comprising transferring the visualized pattern to an image receiving member.

17. The process according to claim 16 further comprising fixing the transferred pattern on the image receiving member.

18. The process of producing a condensate pattern in the configuration of the image pattern of an original having a vaporizable material in at least the imagebearing areas thereof that is adapted to be visualized subsequent to transfer to a transfer member by being contacted with a visible material capable of adhering thereto comprising placing an image-bearing side of the original in contact with a transfer member, heating the original at the image-bearing areas to an extent sufficient to vaporize at least a portion of the vaporizable material, and forming on the facing surface of the transfer member images consisting essentially of condensate of the vaporized material and corresponding to the image-bearing areas of the original by condensing thereon at least a portion of the vaporized material in a pattern corresponding to the image pattern of the original.

- 3 33 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION man; so. 3,792,266 Dated February 12, 1974 Q Robert W. Gundlach It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Page 1, left "column, between lines 7 and .8, above "122] Filed: Nov. 26; 1971", insert --[73] Assignees, Xerox COrPOratwIII Rochester, N.Y. a corporation of New York Column 4, lines9-and l0, "coating" should re'ad -coated- Column 6, line'33l, "or"'should read of-;-'a nd Column 7, line- 6, "material" should read -nia terials--,

Signed and sealed this 20th day of August 197 (SEAL) Attest:

MCCOY M. GIBSON, JR. C. MARSHALL DANN Attesting Officer'- Commissioner-of Patents 

2. The process of forming a reproduction of an original image comprising positioning a freshly-inked original image in face-to-face contact with a sheet of cellulose acetate film, intensely illuminating said original image through said film so that volatile material in the ink of the original image is evaporated and forms a condensate on said film, separating said film from said original image and developing said condensate with a ferro-magnetic powder having a particle size between 4 and 17 microns.
 3. The process of image reproduction comprising positioning an image original carrying volatile material adjacent to a reproducing member, illuminating said image original with illumination energy of between 25 and 150 watt seconds per square inch or reproduction area to evaporate and form a condensate of said volatile material on the reproducing member in the pattern of the orIginal image, and applying a particulate powder of crystal violet to said condensate.
 4. The process of image reproduction comprising positioning an image reproducing member in face-to-face contact with an image original, selectively heating said image original causing volatile materials in said image areas to evaporate from the original and form a condensate on the image reproducing member, developing the condensate with a particulate colorant into a visible image, transferring said visible image to a transfer member and fixing said visible image on the transfer member.
 5. The process of image reproduction as in claim 4 in which the particulate colorant is carbonyl iron powder and the transfer member is a sheet of paper coated with a thermoplastic film.
 6. The process of image reproduction according to claim 5 in which said thermoplastic film is a polyethylene film.
 7. The process of image reproduction according to claim 4 in which the transfer member comprises a thermoplastic layer and the said visible image is fixed on the transfer member by heating the thermoplastic layer so that the image particles become embedded and encapsulated therein.
 8. The process of making a transparent master comprising positioning a transparent plastic sheet in face-to-face contact with an original carrying volatile substance on its image surface, intensely illuminating said original through the transparent plastic sheet so that heat is generated in the image areas of the original producing a condensate of the volatile substance on the transparent plastic sheet, separating said transparent plastic sheet from the original, developing the condensate with a particulate colorant and fixing the particles of the colorant to the plastic sheet.
 9. The process of image reproduction comprising positioning an image-reproducing member facing an image original, selectively heating said image original causing volatile material in image areas to evaporate and form a condensate on the image-reproducing member in image configuration and developing the condensate with a particulate colorant into a visible image.
 10. The process of original image reproduction comprising placing an original carrying a vaporizable material in at least image areas with its image side in contact with a transfer sheet, heating at least the image areas of said original to the vaporization point of said vaporizable material, condensing at least a portion of said vaporized material on the surface of said transfer sheet facing said original and visualizing said condensed material on said transfer sheet by dusting said transfer sheet with a colored particulate material which adheres to said condensed vaporizable material.
 11. The process of reproducing an original image carrying volatilizable material comprising placing an image receiving member in contact with said original image, directing sufficient radiant energy upon said original image to volatilize said material, condensing said material on said receiving member in the configuration of said original image and dusting the condensed material with a colored particulate powder.
 12. The process of reproducing a graphic image drawn upon a surface with material containing infrared absorbent and infrared volatilizable constituents, comprising placing an image receiving member in contact with said graphic image, volatilizing said constituents by directing radiant infrared-rich energy upon said surface, thereupon condensing said constituents on said receiving member in the same configuration as said graphic image, and thereupon visualizing said constituents by applying thereto a highly visible powder, said powder being characterized by mechanical adherence to said constituents.
 13. The process of copying originals which comprises placing an original having a vaporizable material in image areas of the original with its image side in contact with a copy sheet; heating image areas of said original to evaporate said vaporizable material; condensing vaporizable materIal on said copy sheet facing said original; and developing the condensed material on said copy sheet by cascading said copy sheet with colored powder which adheres to said condensed material to form a developed image on said copy sheet.
 14. The process of original image reproduction comprising placing the image side of an original having image-bearing areas and non-image bearing areas thereon adjacent to a transfer sheet, at least the image-bearing areas containing a vaporizable material that is adapted to be visualized subsequent to transfer to the transfer sheet by being contacted with a visible material capable of adhering thereto, heating the original at the image-bearing areas to an extent sufficient to vaporize at least a portion of the vaporizable material, and forming on the adjacent surface of the transfer sheet images consisting essentially of condensate of the vaporized material and corresponding to the image-bearing areas of the original by condensing at least a portion of the vaporized material on said adjacent surface in a pattern corresponding to the image pattern of the original.
 15. The process according to claim 14 further comprising visualizing the pattern of condensed material on the transfer sheet by contacting the condensed material with a visible material capable of adhering thereto.
 16. The process according to claim 15 further comprising transferring the visualized pattern to an image receiving member.
 17. The process according to claim 16 further comprising fixing the transferred pattern on the image receiving member.
 18. The process of producing a condensate pattern in the configuration of the image pattern of an original having a vaporizable material in at least the image-bearing areas thereof that is adapted to be visualized subsequent to transfer to a transfer member by being contacted with a visible material capable of adhering thereto comprising placing an image-bearing side of the original in contact with a transfer member, heating the original at the image-bearing areas to an extent sufficient to vaporize at least a portion of the vaporizable material, and forming on the facing surface of the transfer member images consisting essentially of condensate of the vaporized material and corresponding to the image-bearing areas of the original by condensing thereon at least a portion of the vaporized material in a pattern corresponding to the image pattern of the original. 